Adaptation to cell culture induces functional differences in measles virus proteins.
BACKGROUND
Live, attenuated measles virus (MeV) vaccine strains were generated by adaptation to cell culture. The genetic basis for the attenuation of the vaccine strains is unknown. We previously reported that adaptation of a pathogenic, wild-type MeV to Vero cells or primary chicken embryo fibroblasts (CEFs) resulted in a loss of pathogenicity in rhesus macaques. The CEF-adapted virus (D-CEF) contained single amino acid changes in the C and matrix (M) proteins and two substitutions in the shared amino terminal domain of the phosphoprotein (P) and V protein. The Vero-adapted virus (D-VI) had a mutation in the cytoplasmic tail of the hemagglutinin (H) protein.


RESULTS
In vitro assays were used to test the functions of the wild-type and mutant proteins. The substitution in the C protein of D-CEF decreased its ability to inhibit mini-genome replication, while the wild-type and mutant M proteins inhibited replication to the same extent. The substitution in the cytoplasmic tail of the D-VI H protein resulted in reduced fusion in a quantitative fusion assay. Co-expression of M proteins with wild-type fusion and H proteins decreased fusion activity, but the mutation in the M protein of D-CEF did not affect this function. Both mutations in the P and V proteins of D-CEF reduced the ability of these proteins to inhibit type I and II interferon signaling.


CONCLUSIONS
Adaptation of a wild-type MeV to cell culture selected for genetic changes that caused measurable functional differences in viral proteins.
Bankamp
Bettina
B
Measles, Mumps, Rubella and Herpesvirus Laboratory Branch, Division of Viral Diseases, Centers for Disease Control and Prevention, MS C-22, 1600 Clifton Road, Atlanta, Georgia 30333, USA. bbankamp@cdc.gov
Fontana
Judith M
JM
Bellini
William J
WJ
Rota
Paul A
PA
D000220:Adaptation, Biological / Q000235:genetics*; D000818:Animals; D002522:Chlorocebus aethiops; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral; D016899:Interferon-beta / Q000378:metabolism; D008459:Measles virus / Q000378:metabolism*; D009154:Mutation; D015398:Signal Transduction; D014709:Vero Cells; D014760:Viral Fusion Proteins / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication / Q000235:genetics
D014760:Viral Fusion Proteins; D014764:Viral Proteins; D016899:Interferon-beta